1. Field of the Invention
The present invention relates to an information processor adapted for realizing a small-sized portable computer.
2. Description of the Related Art
In a portable computer having a pen interface with a script input and reproduce function, it is necessary to hold script data which requires a greater storage capacity in comparison with other data such as character code and so forth. More specifically, the sampling rate in a tablet is generally 100 points/second or so, and therefore a total of 400 bytes are needed per second if 2 bytes are allocated to X and Y coordinates of each point. Supposing that 1 stroke (from pen-down to pen-up) is written in 0.2 second on the average, the storage capacity required per stroke amounts to 80 bytes. In an example where 1 character is written with 8 strokes on the average, the total required capacity per character amounts to 80.times.8=640 bytes. Since a character code is expressed by 2 bytes according to the JIS code or Shift JIS code, it follows that the required storage capacity becomes approximately 300 times. Although the amount of script data can be compressed and reduced by curtailing the points thereof, it is still impossible to preserve the data in the storage capacity equal to that for the character code.
In any portable computer for processing script data as described above, it is essential to incorporate a great-capacity memory and also a random access memory due to the necessity of editing and/or partially erasing the script data. In view of this point, the following problems are existent with regard to the read/write memory means used heretofore.
(1) In use of magnetic tape:
The performance is not satisfactory in respect of the random access time and, in reproducing the recorded script data, a considerable time is spent for cueing the same. And in the process of partially erasing the recorded data and rewriting some other data, there is a restriction that the new data needs to be smaller in size than the former data.
(2) In use of magnetic hard disc:
Fundamentally, adequate flexibility is not attainable in interchanging the data with an external apparatus since it is impossible to take out a recording medium and replace the same, whereby the script data is not interchangeable with facility. Script data of a relatively great content requires a memory having a great storage capacity, so that the requisite is not satisfied completely with respect to the storage capacity either.
(3) In use of semiconductor card memory:
When a semiconductor memory is used, it is possible to form both a read-only area, a write-only area and a read/write area in the same card and to store a protected program in the read-only area for prohibition of copying and alteration. However, the storage capacity is generally small and not sufficient to hold the script data.
For enabling a user to see the script data by a variety of methods, the portable computer for processing the script data needs to be capable of performing its operation in various modes such as a real time reproduce mode for reproducing the script data at the same speed as the input speed, a batch reproduce mode for reproducing the data by unitary 10 strokes, and a batch reproduce mode for reproducing the data by unitary 10 seconds.